Multi-variate analysis of elemental data from the Azores archipelago and Great Meteor seamounts

Abstract

Several dredge operations were sucessfully performed during the cruise EMEPC/Açores/G3/2007 along a track from the Azores to the Great Meteor seamounts covering also Plato and Hyeres seamounts. The recovered basaltic rocks are alkaline displaying mainly porphyritic textures with variable vesicularity and olivine, clinopyroxene ± plagioclase phenocrysts. Most samples contain thin veins or vesicles filled with calcite and/or zeolites and careful sample preparation was carried out to exclude low-temperature alteration signature on geochemical data. Following [1] incompatible element ratios (X/Th) were used to be compared with data from the Azores archipelago (GEOROC database) using Principal Component Analysis. Results show a coherent relationship between unaltered basalts from seamounts and those from the Azores Islands and supports previous models based on geophysical data linking these seamounts to the Azores hot spot activity during the last 85 Ma (e.g. [3]). However, the origin of the Azores hot spot is still strongly debated as a consequence of the high variablity in radiogenic isotopic ratios obtained for basalts from the Azores Islands. It is expected that isotopic analysis on samples from the Great Meteor seamounts will shed light on mantle source evolution and oceanic intraplate volcanism.